<template>
  <transition mode="out-in" v-on="on">
    <slot></slot>
  </transition>
</template>
<script lang="ts" setup>
  import { addClass, removeClass } from '@/utils/domUtils';

  defineOptions({ name: 'MenuCollapseTransition' });

  const on = {
    beforeEnter(el) {
      addClass(el, 'collapse-transition');
      if (!el.dataset) el.dataset = {};

      el.dataset.oldPaddingTop = el.style.paddingTop;
      el.dataset.oldPaddingBottom = el.style.paddingBottom;

      el.style.height = '0';
      el.style.paddingTop = 0;
      el.style.paddingBottom = 0;
    },

    enter(el) {
      el.dataset.oldOverflow = el.style.overflow;
      if (el.scrollHeight !== 0) {
        el.style.height = el.scrollHeight + 'px';
        el.style.paddingTop = el.dataset.oldPaddingTop;
        el.style.paddingBottom = el.dataset.oldPaddingBottom;
      } else {
        el.style.height = '';
        el.style.paddingTop = el.dataset.oldPaddingTop;
        el.style.paddingBottom = el.dataset.oldPaddingBottom;
      }

      el.style.overflow = 'hidden';
    },

    afterEnter(el) {
      removeClass(el, 'collapse-transition');
      el.style.height = '';
      el.style.overflow = el.dataset.oldOverflow;
    },

    beforeLeave(el) {
      if (!el.dataset) el.dataset = {};
      el.dataset.oldPaddingTop = el.style.paddingTop;
      el.dataset.oldPaddingBottom = el.style.paddingBottom;
      el.dataset.oldOverflow = el.style.overflow;

      el.style.height = el.scrollHeight + 'px';
      el.style.overflow = 'hidden';
    },

    leave(el) {
      if (el.scrollHeight !== 0) {
        addClass(el, 'collapse-transition');
        el.style.height = 0;
        el.style.paddingTop = 0;
        el.style.paddingBottom = 0;
      }
    },

    afterLeave(el) {
      removeClass(el, 'collapse-transition');
      el.style.height = '';
      el.style.overflow = el.dataset.oldOverflow;
      el.style.paddingTop = el.dataset.oldPaddingTop;
      el.style.paddingBottom = el.dataset.oldPaddingBottom;
    },
  };
</script>
